This invention relates to an electronic signal device for a set of pneumatic tires, more particularly to an electronic signal device which has an electrical sound producing unit for the purpose of alarming when one of the tires is deflated to a pressure below a predetermined proper pressure and a display means to indicate which of the tires is seriously deflated.
Signal devices for pneumatic tires are known in the art U.S. Pat. No. 4,814,745, owned by the applicant of this invention, discloses a pressure gauge to be attached to a tire after the tire is inflated. The device includes an electric alarming unit mounted in a cap-like casing, which makes a sound whenever the tire is deflated to a pressure below a predetermined proper pressure. In an ordinary car employing this invention, one would have to listen carefully as to where the sound is coming from to determine which of the tires is seriously deflated. However, if the vehicle in question is a 12-wheeler truck, this device is not practical, since the sound generated by the device may not be audible to the driver due to the fact that the tires may be too far away.